Tom Cruise performed the sequence where Ethan Hunt scales the outside of the Burj Khalifa tower himself without the use of a stunt double. The Burj Khalifa tower is the tallest building in the world at 2,722 feet, or 829.8 meters. Cruise dangled outside the tower at approximately 1,700 feet, or 518 meters.
Director Brad Bird specifically wanted every gadget to break or malfunction in the film.
During production, Tom Cruise did the majority of his own stunts, including the skyscraper sequence(s), to show the audience it was actually him. This would allow director Brad Bird to have more capabilities with camera angles, and not having to hide the fact that it is a stuntman doing the stunts.
According to Tom Cruise, he was happy to hear that they were using a subtitle in the film's heading instead of a number like the prior three films did. Cruise has never been a fan of a number at the end of the film's sequel titles as he's always considered each film as a stand alone feature in the Mission: Impossible film franchise.
The windows removed from Burj Khalifa were carefully chipped away by two workers with hammers, working from a window washing platform outside the building.
Brad Bird: [A113] Ethan uses the call sign "Alpha 113" and "A113" appears on Hanaway's ring. A113 is a frequent in-joke and Easter egg appearing in films produced by Pixar as well as films created by alumni of California Institute of the Arts, based on one of the room numbers for the character animation BFA program. Director Brad Bird is both a Cal Arts alumnus and Pixar movie director, and he has worked an "A113" reference into every one of his feature films, as well as some of his television work.